Rapid Communication Activation of Protein Kinase C Inhibits Kainate‐Induced Currents in Oocytes Expressing Glutamate Receptor Subunits

Abstract
The effect of protein kinase C (PKC) activation on maximal kainate (KA)‐induced currents was studied in Xenopus oocytes expressing the glutamate receptor (GluR) subunits GluR3, GluR1+3, GluR2+3, and GluR6. The PKC activator phorbol 12‐ myristate 13‐acetate (PMA) inhibited peak KA responses in a time‐dependent manner. The magnitude of inhibition was greatest in GluR6‐expressing oocytes. Desensitizing KA currents characterized by a peak, transient current followed by a slower, desensitizing current were observed in oocytes expressing GluR3 and GluR 1+3 receptors. PMA inhibited the desensitization, and this effect could be observed before PMA's inhibition of peak current amplitude. PMA‐mediated inhibition of both desensitization and peak current amplitude was prevented by intracellular injection of the protein kinase C (PKC) inhibitor peptide. These results suggest that the function of GluRs is regulated by PKC‐dependent phosphorylation